Grant Erwin wrote
There is no direct way to find a seller's internal
ebay number. If they have an "ebay store" then to get the sellers id place your
cursor over their store in the listing and see what the url is in the status
bar. It will have id/1580591

Grant,
You don't need the ebay store for this. Goto search by seller and at
the bottom of the page search for more than one ebay id (yours plus
the other guy). It will show the id numbers in the url.

Regards,
dave